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Monday, 15 October 2007

Genographic Project results

I've just received the results for my maternal line. Rather surprised to see the line doesn't go anywhere near China and that I'd find some rellies among Australian aborigines.

Rather curious about my paternal lineage now. I can't test for paternal lineage with my DNA since I don't have a Y chromosome. I think I know what dad will be getting for Christmas 8)

"Your DNA results identify you as belonging to a specific branch of the human family tree called haplogroup M*.

The map above shows the direction that your maternal ancestors followed as they set out from their original homeland in East Africa. While humans did travel many different paths during a journey that took tens of thousands of years, the lines above represent the dominant trends in this migration.

Over time the descendants of your ancestors were the first modern humans to leave Africa and headed east, moving across the Arabian Peninsula, through the Indian subcontinent and on to eastern Asia and Australasia.

Mitochondrial Eve: The Mother of Us All

Ancestral Line: "Mitochondrial Eve"

Our story begins in Africa sometime between 150,000 and 170,000 years ago, with a woman whom anthropologists have nicknamed "Mitochondrial Eve."

She was awarded this mythic epithet in 1987 when population geneticists discovered that all people alive on the planet today can trace their maternal lineage back to her.

But Mitochondrial Eve was not the first female human. Homo sapiens evolved in Africa around 200,000 years ago, and the first hominids—characterized by their unique bipedal stature—appeared nearly two million years before that. Yet despite humans having been around for almost 30,000 years, Eve is exceptional because hers is the only lineage from that distant time to survive to the present day.

Which begs the question, "So why Eve?"

Simply put, Eve was a survivor. A maternal line can become extinct for a number of reasons. A woman may not have children, or she may bear only sons (who do not pass her mtDNA to the next generation). She may fall victim to a catastrophic event such as a volcanic eruption, flood, or famine, all of which have plagued humans since the dawn of our species.

None of these extinction events happened to Eve's line. It may have been simple luck, or it may have been something much more. It was around this same time that modern humans' intellectual capacity underwent what author Jared Diamond coined the Great Leap Forward. Many anthropologists believe that the emergence of language gave us a huge advantage over other early human species. Improved tools and weapons, the ability to plan ahead and cooperate with one another, and an increased capacity to exploit resources in ways we hadn't been able to earlier, all allowed modern humans to rapidly migrate to new territories, exploit new resources, and outcompete and replace other hominids, such as the Neandertals.

It is difficult to pinpoint the chain of events that led to Eve's unique success, but we can say with certainty that all of us trace our maternal lineage back to this one woman.

Haplogroup M: The Coastal Migrants

Ancestral line: "Eve" > L1/L0 > L2 > L3 > M

Your next signpost ancestor is the woman whose descendants formed haplogroup M. Haplogroup M comprises one of two groups that were created from L3.

One of these two groups, haplogroup N, moved north out of Africa and left the continent across the Sinai Peninsula, in present-day Egypt. Faced with the harsh desert conditions of the Sahara, their ancestors likely followed the Nile basin, which would have proved a reliable water and food supply in spite of the surrounding desert and its frequent sandstorms. The ancient members of haplogroup N spawned many sub-lineages that went on to populate much of the rest of the globe. They are found throughout Asia, Europe, India, and the Americas.

Your haplogroup, M*, constitutes the other group that split off from L3, and gave rise to the first wave of modern humans to make a successful exodus from Africa. These people likely left the continent across the Horn of Africa, where a narrow span of water between the Red Sea and the Gulf of Aden separates the East African coastline from the Arabian Peninsula at Bab-el-Mandeb. The short ten miles would have been easily navigable for humans possessing early maritime technologies. This crossing constituted the start of a long coastal migration eastward across the Middle East and southern Eurasia, eventually reaching all the way to Australia and Polynesia.

Haplogroup M* is considered an east Eurasian lineage, as it is found at high frequencies east of the Arabian Peninsula. Members of this group are virtually absent in the Levant (a coastal region in what is now Lebanon), though they are present at higher frequencies in the south-Arabian Peninsula at around 15 percent. Because its age is estimated at around 60,000 years old, members of this group were likely the first humans to leave Africa, and they likely did it heading east. Haplogroup M is found in East Africa, though at much lower frequencies than its subgroup M1. It gives the appearance of a more recent age in eastern Africa than in Asia which is likely the result of smaller populations in Africa, which would have reduced genetic diversity and would therefore appear more recent.

Your haplogroup is prevalent among populations living in the southern parts of Pakistan and northwest India, where it constitutes around 30 to 50 percent of the mitochondrial gene pool, depending on the population. Conversely, the M* haplogroup is absent or rarely found amongst people living west of the Indus Valley, and is found at low frequencies in the Central Asian populations, around 10 to 15 percent. The wide distribution and greater genetic diversity east of Indus Valley indicates that these haplogroup M*-bearing individuals are the legacy of the first inhabitants of southwestern Asia. These people underwent important expansions during the Paleolithic, and the fact that some East Asian haplogroup M* lineages match those found in Central Asia indicates much more recent (i.e., not founder) mixture into the area from the east.

Haplogroup M* has several sub-branches which exhibit some geographic specificity. Subgroup M1 is found at high frequency in East Africa, at around 20 percent in many populations. Because haplogroup M* itself is almost entirely absent from the region, M1 individuals likely represent migrations back into the continent from the Arabian Peninsula after people had left Africa. M2-M6 are characteristic Indian sub-groups. Haplogroup M7 is distributed across the southern part of East Asia, and two of its own daughter-groups, M7a and M7b2, are representative of Japanese and Korean populations, respectively. M7 individuals reach frequency in southern China and Japan of around 15 percent, and are found at lower frequencies in Mongolia. The old age of this branch indicates a pre-Jomon contribution to the mitochondrial gene pool in those areas."